1. Field of Invention
The present invention relates to a light source device incorporated into an exposure device utilized in a manufacturing process for a semiconductor or a liquid crystal substrate, for a color filter, and the like.
2. Description of Related Art
In a manufacturing process for a semiconductor, a liquid crystal substrate or a color filter, shortening of treatment time and batch exposure of articles to be treated having a large surface area are in demand. In response to this demand, a high-pressure discharge lamp with greater ultraviolet light emission intensity into which a large input power can be entered is proposed. However, when the input power into the high-pressure discharge lamp is increased, the load on the electrodes is increased and the problem results that the high-pressure discharge lamp is blackened due to materials evaporating from the electrodes so that a short lifespan results.
FIG. 13 shows a light source device as described in JP-A-61-193358. As shown in FIG. 13, this light source device 100 is a device where an electrodeless discharge lamp 104 is arranged within an ellipsoidal reflector 101; a laser beam is radiated into the discharge vessel of the discharge lamp 104 via a hole 102 in the side surface of the ellipsoidal reflector 101; and the discharge gas enclosed within the discharge vessel is excited and produces light. In this light source device 100, because there is no electrode in the discharge lamp 104, the problem mentioned above can be solved.
However, the light source device 100 described in JP-A-61-193358 has the light entrance hole 102 and a light exit hole 103 for the laser beam in the side surface of the ellipsoidal reflector 101, and when ultraviolet radiation generated from the electrodeless discharge lamp 104 is focused by the ellipsoidal reflector 101, because of the holes 102, 103 on the reflecting surface, there is the problem that the ultraviolet radiation cannot be efficiently utilized. Further, the laser beam enters into the electrodeless discharge lamp 104 from a direction intersecting the optical axis X of the ellipsoidal reflector 101, and the discharge extends in a lateral direction (direction intersecting with the optical axis X), and the discharge occurs even in a region shifted from the focal point of the ellipsoidal reflector 101. This causes the problem that the ultraviolet radiation cannot be efficiently utilized because the ultraviolet radiation is not accurately reflected.
FIG. 14 shows a light source device as is described in US 2007/0228300 A1. As shown in FIG. 14, this light source device 200 is a device where an electrodeless discharge lamp is arranged within a reflector 201 and a laser beam enters into the discharge vessel 203 of the discharge lamp via an opening 202 at the apex of the reflector 201, and discharge gas enclosed in the discharge vessel 203 is excited and produces light. In this light source device 200, because there is no electrode in the discharge lamp, the above mentioned problem can be solved.
In the light source device 200 described in US 2007/0228300 A1, the laser beam entering into the reflector 201 from the opening 202 at the apex of the reflector 201 is reflected by the discharge vessel 203 and the discharge 204 is generated. However, a portion of the laser beam passes through the discharge 204 and passes through the discharge vessel 203, as well, and the laser beam is radiated onto the irradiation surface along with the radiant light generated by the discharge. Consequently, the problem results that the article to be treated on the irradiation surface is damaged due to this undesired effect by the laser beam.
FIGS. 15 &16 show configurations for the purpose of solving the problem of the light source device 200 shown in US 2007/0228300 A1. In the configuration shown in FIG. 15, a laser beam entering from the opening side for emitting light from the reflector 205 is reflected by the reflector 206; is radiated into the reflector 205; discharge gas filled in the discharge vessel is excited and discharge is generated; and the light generated by the discharge is reflected by the reflector 208 and is emitted.
In the configurations shown in FIGS. 15 & 16, the problem in the light source device shown in FIG. 14 can be solved. However, in the configurations shown in FIGS. 15 & 16, the reflectors 206, 208 require wavelength selectivity and manufacturing is difficult, and there are cases where the cutting of the wavelengths cannot be accurately done. In addition, a part of the radiant light is absorbed by the reflector 206 and a part of the radiant light is absorbed by the reflector 208; therefore, there is the problem that the radiant light cannot be efficiently utilized.